Midlife

Listen closely and you'll hear them rust!

Excellent!

I agree. Check the clearance when the transmission is in Reverse, not neutral! Backup lights don't work in neutral.

Figure what it would cost to replace the car (i.e. how much is would cost if you had to buy a replacement in similar condition) and add 25%.

West Coast Cougars has a good video showing a replacement of a roof skin. Interesting stuff! I'd never tackle that myself!

16 to 18 gauge is more than adequate.

Those 2 statements are correct.

For the optional trunk lamp.

Possible...look for a thin purplish wire tied into the black/green thick wire at the ignition switch connector or at a large OEM splice above the switch connector. Check to see what resistance you have been the ignition switch pin and the dash cluster pin: should be 10 ohms or so. You can also check for voltage at the dash cluster pin: 12V, but the presence of voltage does not necessarily mean you'll have current due to high resistance.

Only grounding to the case, and the power output from the CVR is shared by all 3 gauges. Your input power to the CVR or its ground may also be suspect; that is all there is. I've found that the resistor wire feeding the dash cluster pin needs to be re-crimped, as often times it reads well above the nominal 10 ohms from the ACC source at the ignition switch.

CV: are those two dash clusters supposed to be OEM? I can tell you right now that the 1969 is certainly not an OEM dash cluster.

The connectors to the tail-lights are probably behind the driver's side kick panel or just above it. On a 69, there are two 3 pin plugs (flat---you want to look at the red one); on a 70 there's a red and white four pin plug (square). Orange/blue wire is right side light; green/red is left side light.

There is a connector for the rear tail lights between the tail-light harness and the underdash harness. From 10+ years working on these harnesses, I would place more emphasis on a broken wire (probably twisted splice by a previous owner) than on the molded connectors. Most breaks in tail-light harnesses are in the door sill area where someone used a longer screw than necessary and pierced the harness. YMMV, but the above is what is more commonly seen.

Brake light and turn signal are shared on the rear on one filament; running lights are on the second filament. So yes, the brake and turn signals are mixed on the turn signal switch; even more reason to suspect the TSS.

Just reading this thread, I think y'all are simply off your rockers. Someone had to say it...